Slow-strain-rate (SSR) and constant-load (CL) stress corrosion cracking (SCC) tests were performed using two Zr alloys in neutral and acidic environments at temperatures ranging from ambient to 90°C. The cracking susceptibility was determined with and without the application of the controlled cathodic potentials. The metallography and fractography of the tested specimens were conducted by optical microscopy and scanning electron microscopy (SEM), respectively. The results of CL SCC testing showed no failure in either environment. SCC testing by the SSR technique revealed increased ductility in the 90°C acidic environment. The magnitude of failure stress was significantly reduced due to the synergistic effect of temperature and pH. The application of cathodic controlled potential to the test specimen during SSR testing did not influence the ductility parameters and the failure stress. Even though no effect of cathodic charging on the cracking susceptibility of Zr alloys was observed, it is interesting to note that the test specimens showed damage in their gage sections under controlled potential (Econt) during both CL and SSR testing. Some indications of secondary cracking due to Econt were observed by optical microscopy. Fractographic evaluations by SEM showed dimpled microstructures indicating ductile failures in both test environments.

Subject
Acids, Scanning electron microscopy, Test methods, Materials, Optical microscopy, Stress, Mechanical failure, Test environments, Zirconium alloys, Caustic stress corrosion cracking, Stress corrosion cracking, Ductility, Test specimen
Keywords:
Zirconium alloys, stress corrosion cracking, constant-load, slow-strain-rate, fractography
© 2004 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2004
Association for Materials Protection and Performance (AMPP)
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